1. Field of the Invention
This invention generally relates to an optical navigator and, more particularly, to an image processing method of an optical navigator and an optical navigator using the same.
2. Description of the Related Art
When the brightness of images captured by the image sensor of an optical navigator, e.g. a mouse, is not within a predetermined range, it is generally necessary to adjust an exposure of the optical navigator to allow the image sensor thereof to capture images having sufficient brightness. For example, U.S. Pat. No. 6,297,513 discloses “Exposure Servo for Optical Navigation over Micro-Textured Work Surface” that controls an exposure control parameter according to an average illumination of images captured by an optical navigation device. The control method includes the steps of: (a) initially varying the setting of the exposure control parameter until average illumination is approximately 50% of its maximum possible value; (b) retaining, if correlation data associated with navigation are satisfactory, the current exposure control parameter setting, otherwise further varying the exposure control parameter setting to obtain satisfactory correlation data; (c) storing the current average level of illumination; (d) navigating with the current exposure control parameter setting to obtain an amount of relative motion, wherein the navigation includes storing latest values of average illumination and the correlation data; and (e) adjusting the setting of the exposure control parameter.
However, the aforementioned control method varies the exposure control parameter only when the average illumination of images is not within a predetermine range so as to adjust the illumination of images of a work surface having different reflection intensities. When the average illumination of images fulfills the requirement, images captured by the optical navigation device will not be further processed, and therefore it is not able to effectively increase the dynamic processability of reflected images of a work surface.
Accordingly, it is necessary to further provide an image processing method of an optical navigator so as to increase the resolution of the image of a work surface having different reflection intensities and further to increase the dynamic processability of reflected images from the work surface.